---
title: every acre is one of fifteen things
canonical_url: https://ensurance.app/guide/every-acre-is-one-of-fifteen-things
markdown_url: https://ensurance.app/guide/every-acre-is-one-of-fifteen-things.md
subtitle: "how land cover becomes an ecosystem type, and why the list stops at fifteen"
category: natural-capital
---

# every acre is one of fifteen things

*how land cover becomes an ecosystem type, and why the list stops at fifteen*

A **land cover classification** is a list of the kinds of surface a sensor can tell apart from above: forest, water, wetland, herbaceous, shrub, barren, ice, developed, cultivated. The US National Land Cover Database sorts the whole country into nine such broad class groups at thirty-meter resolution from Landsat. An ecosystem typology is a different list, built from the ground up: it sorts places by how they work, what drives them and what lives in them. The IUCN Global Ecosystem Typology does that in realms, biomes and functional groups. A valuation needs something in between: coarse enough to carry a dollar figure per acre, fine enough to tell a peat bog from a pine stand.

Stand on a ridge above a town in the Appalachians. The satellite sees "forest" on the slope and "wetland" at the foot of it. The ecologist sees a temperate deciduous forest and a palustrine wetland fed by groundwater. The county sees two parcels. The valuation needs to know that the slope is Temperate Forests and the foot is Inland Wetlands, because those are the rows in the value table where a year of their work has been valued. Each is a stock, a living system with an extent, a character and a condition; what each does every year is its flow. RealValue makes the flow legible in dollars beside what the stock costs to hold. The stock exists whether or not anyone classifies it. [Ensurance](/?from=guide) funds the stock. It is not the row. Those who depend on the flows fund the asset that makes them, and the asset kept whole keeps making them. [Ensure the asset to ensure the flows](/guide/ensure-the-asset-to-ensure-the-flows?from=guide) is that loop in full.

:::johnson
**land cover is what the satellite sees. an ecosystem type is what the valuation can use.** — Twenty-seven typologies were read and seven kept. The crosswalk that came out of them, fourteen types and then fifteen, is the list a dollar per acre per year can attach to.

[see the fifteen →](/natural-capital/stocks?from=guide)
:::

## three ways to sort the same ground

| Sorted by | Examples | Built for | What it cannot do alone |
|---|---|---|---|
| What a sensor sees (land cover) | NLCD's nine broad groups at 30 m; ESRI's nine classes from Sentinel-2; Dynamic World's nine at 10 m, in near real time | Mapping the whole surface, every year, cheaply | Tell a bog from a swamp, or a tropical forest from a boreal one, both "forest" |
| How the system works (ecosystem typology) | IUCN GET 2.0's realms, biomes and functional groups; IUCN Habitats; One Earth bioregions; ecoregions | Conservation status, Red Lists, national accounts | Carry a per-acre dollar figure; the classes run far finer than the value records |
| What has been valued (valuation databases) | ESVD's biomes, which follow TEEB; FEMA's nine priced land covers | Attaching dollars per acre per year | Cover every place; FEMA prices nine land covers and the crosswalk marks grassland, shrubland, desert and the poles "not covered" |

Each list is right for its job. None of them is the one a parcel valuation needs, which is a list where nearly every entry shows in land cover data, every entry is understood as a living system, and every entry has value records filed under it.

## twenty-seven read, seven kept

The framework behind RealValue read 27 land cover classifications and ecosystem typologies, by the Field Manual's count, and judged each on three things: does it serve ecosystem service valuation, does it map onto real assets as the law and the market already hold them, and do corporate financial and ESG disclosures use it. The 27 run from the Anderson system, through FAO's Land Cover Classification System, Copernicus, EPA ecoregions, the WWF Global 200, NOAA's coastal classifications, to SEEA, TEEB and TNFD.

| Step | What | Why |
|---|---|---|
| Read | 27 land cover classifications and ecosystem typologies | Relevance to valuation, real assets and disclosure |
| Kept | 7 for the crosswalk: IUCN GET 2.0, ESVD, FEMA ESV, IUCN Habitats, ESRI Land Cover, NLCD, Dynamic World | The ones valuation and disclosure cite, and the ones a parcel can be mapped in |
| Weighted | IUCN GET 2.0, ESVD, FEMA ESV | They rest on the Millennium Ecosystem Assessment, TEEB and the IUCN Red Lists, or were built for ecosystem service valuation |
| Scope | Land-centric; open and deep sea set aside in the first version, with the BlueValue database named for marine work | Terrestrial restoration and conservation came first; Marine Systems was added as the fifteenth type |

Of the seven, IUCN GET 2.0 is the typology SEEA EA, TNFD and the IUCN Red List of Ecosystems reference; ESVD's biomes are the ones its value records are filed under; FEMA's land covers are the ones with federally accepted per-acre figures. The IUCN Habitats scheme is the reference list the Red Lists use. ESRI, NLCD and Dynamic World are the maps a parcel can actually be seen in.

## the crosswalk

Here is what the crosswalk does for four of the fifteen, from the worksheet behind the Field Manual:

| BASIN stock | IUCN GET 2.0 | ESVD 2020 | FEMA 2022 | NLCD |
|---|---|---|---|---|
| Inland Wetlands | TF1 palustrine wetlands; F3 artificial fresh waters | Inland wetlands | Inland wetlands | Wetlands, water, forest |
| Temperate Forests | T2 temperate-boreal forests and woodlands | Temperate forests (boreal inside) | Forest | Forest |
| Coastal Systems | FM1 semi-confined transitional waters; MT1 shoreline systems; MT2 supralittoral coastal systems; MFT1 brackish tidal systems; the marine shelf and the anthropogenic shoreline and marine rows | Coastal systems, including wetlands | Coastal wetlands; beaches and dunes | Water, wetlands, forest |
| Grasslands | T4 savannas and grasslands | Grass and rangeland | Not covered | Herbaceous |

Read a row left to right and you can see what each stock is for. Inland Wetlands is the row where a palustrine wetland in IUCN's terms, an "inland wetland" in ESVD's value records and FEMA's priced "inland wetlands" all land, so a figure from either value source can be carried to a marsh in Ohio, filed under the type IUCN also recognizes, with its lineage intact. Read the Grasslands row and you can see what the list admits: FEMA has no priced figure for grassland, so that cell reads "not covered", and the valuation says so rather than borrowing a forest number.

Boreal Forests sits inside ESVD's temperate forests biome in the 2020 database and was split out in 2023. The crosswalk notes the split. A list that is honest about its sources has to be honest about them changing. Two rows have blank map cells: Subterranean does not show in ESRI, NLCD or Dynamic World, and Marine Systems is not in the crosswalk at all. Those two are understood from the ground and from the value records, not from above.

## the fifteen, defined

The Field Manual gives each stock a definition that standardizes the language across the frameworks it read. Four of them, paraphrased closely, so you can hear the register:

- **Urban Open Space.** Vegetated areas in urban settings, where at least 80% of the land is covered by vegetation and less than 20% is impervious surface.
- **Inland Wetlands.** Ecosystems where the soil is periodically saturated or covered by water: swamps, marshes, peatlands, bogs, floodplains, and wetlands dependent on groundwater.
- **Coastal Systems.** Coastal and transitional habitats including tidal wetlands, beaches and dunes; estuaries appear in several types, and shellfish reefs, coral reefs and deepwater habitats fall under the marine scope.
- **Boreal Forests.** Also called taiga: high northern latitudes, long cold winters, short summers, dominated by spruce, fir and pine, with a sparse understory, significant for carbon storage and habitat.

The full fifteen, flat:

Cultivated & Developed · Urban Open Space · Rural Open Space · Rivers & Lakes · Inland Wetlands · Tropical Forests · Temperate Forests · Boreal Forests · Coastal Systems · Marine Systems · Grasslands · Shrublands · Polar & Alpine · Desert · Subterranean

Each is a page at [/natural-capital/stocks](/natural-capital/stocks?from=guide), and the 2025 post [the 15 ecosystem types that underpin your portfolio](/guide/15-ecosystem-types-natural-capital-stocks?from=guide) gives each a line on what it does. The source typologies would sort these into terrestrial, freshwater and marine realms, and that is useful to an ecologist. It is one more thing to learn for everyone else, so the list stays flat.

## why fifteen and not fourteen, or a hundred

The appendix that documents the crosswalk says fourteen. The stocks page and the manual say fifteen. Both are right about their own version: the first crosswalk was deliberately land-centric and set open and deep sea aside, pointing marine work to BlueValue. Marine Systems was added as the fifteenth. When you see a count in this framework, read it as a version, not a law.

Why not a hundred? IUCN GET 2.0's functional groups run far finer than fifteen, and an ecologist is right to want them. But the value records are not filed that finely. ESVD files under biomes; FEMA under nine land covers. A list with more entries than the records can fill is a list with empty rows, and a valuation that borrows across empty rows is guessing. Fifteen is roughly where the typologies and the value records still meet. Finer detail goes into the polygon's characteristics, which is where the IUCN functional group, the One Earth bioregion and the ecoregion get recorded; [the same acre is not the same acre](/guide/the-same-acre-is-not-the-same-acre?from=guide) covers that.

## what a stock is not

A stock is not a parcel. A parcel can hold three stocks: the slope, the foot, the creek. The valuation delineates each by acreage. A stock is not a biome; a biome is a continent's worth of one kind of system, and the value of an acre of it depends on which acre. And a stock is not a pixel; thirty meters of "forest" is a measurement, not a place. The stock is the living system on this ground, of this type, in this condition.

## frequently asked questions

### what is a land cover classification?

A land cover classification is a scheme for sorting the Earth's surface into classes a remote sensor can distinguish, such as forest, water, wetland, shrubland, developed and cultivated. The US National Land Cover Database uses nine broad class groups at thirty-meter resolution. It tells you what covers the ground; it does not by itself tell you how the ecosystem works or what it has been valued at.

### what is the difference between land cover and an ecosystem type?

Land cover is what the surface looks like from above. An ecosystem type is a kind of living system, defined by how it functions and what lives in it. A valuation uses a list in between: fifteen types, most of them visible in land cover data, each understood as a system, each with value records filed under it.

### why does the framework use fifteen ecosystem types?

Because fifteen is where the ecological typologies and the valuation databases still agree. Twenty-seven classifications were read and seven kept, weighted toward IUCN GET 2.0, ESVD and FEMA ESV. More classes than the value records can fill would leave empty rows; fewer would mix a bog with a pine stand.

## next

The work the places do: [nineteen things a place does](/guide/nineteen-things-a-place-does?from=guide).

If you steward land and want to know which of the fifteen is on it, [land stewards](/solutions/land-stewards?from=guide&topic=stocks-and-flows) shows what we do with a parcel. If you can already name the place, [tell us which](/contact?from=guide&topic=stocks-and-flows).

## sources

[BASIN Field Manual, Land Cover Classification & Ecosystem Typologies](https://docs.basin.global/appendix/land-cover-classification-and-ecosystem-typologies) — 27 sources evaluated, 7 selected, the weighting, the land-centric scope and the crosswalk.

[BASIN Field Manual, Ecosystem Definitions](https://docs.basin.global/core-benefits/core-benefits-framework/stocks-ecosystems/ecosystem-definitions) — the fifteen definitions paraphrased above.

[BASIN Field Manual, IUCN Global Ecosystem Typology 2.0](https://docs.basin.global/appendix/land-cover-classification-and-ecosystem-typologies/ecosystem-classification-frameworks/iucn-global-ecosystem-typology-2.0-iucn-get-2.0), [ESRI Land Cover](https://docs.basin.global/appendix/land-cover-classification-and-ecosystem-typologies/ecosystem-classification-frameworks/esri-land-cover), [Dynamic World](https://docs.basin.global/appendix/land-cover-classification-and-ecosystem-typologies/ecosystem-classification-frameworks/dynamic-world), [USGS NLCD](https://docs.basin.global/appendix/land-cover-classification-and-ecosystem-typologies/ecosystem-classification-frameworks/usgs-national-land-cover-database-nlcd) — the framework pages for the three-ways table.

[BASIN RealValue Worksheet, Land Cover / Ecosystem Cross Reference and Land Cover Sources](https://docs.google.com/spreadsheets/d/1-Ho1C5J2TCFnSJnkSbNXvBldMIUZGZyll3e6kSwazT4/edit) — the crosswalk table and the source list; version dated 8 February 2024; CC BY-NC-SA 4.0.

[IUCN Global Ecosystem Typology 2.0](https://global-ecosystems.org/) — realms, biomes and ecosystem functional groups.

[Dewitz, J. 2021. National Land Cover Database (NLCD) 2019 Products. U.S. Geological Survey.](https://www.usgs.gov/programs/national-geospatial-program/land-cover) — the class groups at 30 m.

[de Groot, R., Brander, L., Solomonides, S. 2020. Update of global ecosystem service valuation database (ESVD).](https://www.es-partnership.org/esvd/) — biomes following TEEB.

[FEMA. 2022. Ecosystem Service Value Updates.](https://www.fema.gov/sites/default/files/documents/fema_ecosystem-service-value-updates_2022.pdf) — the nine priced land cover types.

## the series

1. [the stocks and flows of natural capital](/guide/the-stocks-and-flows-of-natural-capital?from=guide) (read first)
2. [every acre is one of fifteen things](/guide/every-acre-is-one-of-fifteen-things?from=guide)
3. [nineteen things a place does](/guide/nineteen-things-a-place-does?from=guide)
4. [where the dollar per acre comes from](/guide/where-the-dollar-per-acre-comes-from?from=guide)
5. [the same acre is not the same acre](/guide/the-same-acre-is-not-the-same-acre?from=guide)
6. [flows over stocks](/guide/flows-over-stocks?from=guide)
7. [ensure the asset to ensure the flows](/guide/ensure-the-asset-to-ensure-the-flows?from=guide)